public class AuthenticationServlet extends HttpServlet
{
    private String userName;
    private String password;

    protected doPost(HttpServletRequest req, HttpServletResponse resp)
           throws ServletException, IOException
    {
        userName = request.getParameter("userName");
        password = request.getParameter("password");
        authenticateUser(userName,password);
        ......
    }
}

显然，正如有人在自动化负载测试中发现的那样，单例和缺乏同步会导致安全问题。

About 3 years ago I built a site for a somewhat large non-profit organization in our state. When it came time to deploy the application to their web host server, I noticed an odd file named "cc.txt" or something obvious like that in their public site. It was under their web root, was getting served, and was a csv file of all their donor's names, addresses, credit card numbers, expiration dates, and CVV/CVC codes. I cannot count the number of times I brought the issue up - first to my boss, then our company accountant, the client's IT director, finally the client's President. That was 3 years ago. The file is still being served, it can even be googled. And it's been updated. I tend not to respond to their donation solicitations when I get them.

一个“安全”的网站，每个页面都是加密的，但登录页面!

意外地将数据库根密码提交给源代码控制。这很糟糕，因为它是Sourceforge上的源代码控制。

不用说，密码很快就改了。

在这里根据记忆来解释，但它很接近……

<form action="secretpage.html" id="authentication"          
      onsubmit="return document.forms.authentication.password.value == 's3cr3t'">
    Enter password: <input type="password" name="password"><br>
    <input type="submit" name="Login" >
</form>

我认识的一个家伙用这个来保护他网站的“私人区域”。起初，他不愿意相信我，甚至他的浏览器都有这个不可靠的“查看源代码”功能。

当我13岁的时候，我的学校为学生开设了一个社交网络。不幸的是，我发现了一个安全漏洞，可以将URI更改为另一个用户id，如“?”userID=123”，并为该用户登录。显然，我告诉了我的朋友们，最后学校的社交网络充满了色情。

不过我不推荐。